The present invention relates to an air conditioning device or air heating device for power vehicles. More particularly, it relates to an air conditioning device which has a control member formed advantageously as an air-regulating flap, an electric servomotor or adjusting motor arranged to drive the control member, and a temperature regulator having a temperature sensor and acting upon the electric motor.
Devices of the above mentioned general type are known in the art. One such device is disclosed, for example, in the U.S. Pat. No. 2,284,764. This device has a warm air supply passage and a cold air supply passage which both merge into an air passage in the interior of the vehicle. In the region of transition, the above mentioned control member, formed as an air-regulating flap, is turnably mounted, and thereby blocks one or the other supply passage relative to the air passage. The air-regulating flap is adjustable by the electric adjusting motor via a reduction transmission. The adjusting motor is connected with a control device having at least one temperature sensor. It cannot be excluded that the control device has a defect, and that the adjusting motor forces the air-regulating flap to one of its two possible positions and, particularly when the reduction transmission is formed as a worm transmission, fixedly holds the flap in its position. When, in the event of freezing temperatures, the warm air supply passage is blocked because of such defect, it is not possible to defrost the windshield. In modern air conditioning or air heating devices, the control device is provided with transistors. When a defect occurs in the transistors, an expert, particularly in electronics, must be found. Such experts are not available as often as mechanics.
In the air conditioning device disclosed in U.S. Pat. No. 4,216,822, a vaporizer is arranged in a passage behind a blower which aspirates air and completely fills the cross section of the passage. A heater through which motor-cooling water flows is arranged behind the vaporizer at a distance therefrom and only partially fills the cross section of the passage, so that a bypass cross section remains free. A regulating flap is arranged in the passage such that the bypass cross section can be selectively closed or opened to any width. The regulating flap can be turned, as described in U.S. Pat. No. 2,284,764, with the aid of an electric adjusting motor and a reduction transmission. It is not guaranteed there that, in the event of defective control device or adjusting motor, the temperature of the air, at least for defrosting of windshields and heating the interior of the vehicle, can be adjusted.